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java class for JPEG image manipulation

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Joined: 2006-11-13

java class for JPEG image manipulation
that will allow me to take a JPEG at one resolution and rescale it to a different resolution

When the image files are uploaded, my program area doesn't want the higher resolutions

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Joined: 2003-07-24

I recently wrote a simple little app to scale a set of images... perhaps this will help.

public static void main(String[] args) {
try {
final File srcdir = new File(args[0]);
final File destdir = new File(args[1]);
final String extension = args[2];
final float scale = Float.parseFloat(args[3]);

final File[] srcfiles = srcdir.listFiles(new FileFilter(){
public boolean accept(File f){
return(f.isFile() && f.getName().toLowerCase().endsWith(extension.toLowerCase()));

for (File file : srcfiles) {
final BufferedImage image =;
final int w = (int)((float)image.getWidth() * scale);
final int h = (int)((float)image.getHeight() * scale);
final Image scaledimg = image.getScaledInstance(w, h, Image.SCALE_SMOOTH);

final BufferedImage scaledbi = new BufferedImage(scaledimg.getWidth(null),scaledimg.getHeight(null),BufferedImage.TYPE_INT_RGB);
scaledbi.getGraphics().drawImage(scaledimg, 0, 0, null);

final File destfile = new File(destdir,FilenameUtils.removeExtension(file.getName()) + "_" + w + "x" + h + extension);
ImageIO.write(scaledbi, "jpeg",destfile);

System.out.println("Scaled: " + file + " --> " + destfile);

} catch(Exception ex){ex.printStackTrace();}

You should notice the getScaledInstance() method... that is probably what you are looking for. This is all standard Java 5 core API.

Good luck.

PS: sorry about the code formatting.

Joined: 2006-11-13

Thanks cjstehno.